Radio station center tuning push-button control



Oct. 3, 1939. sT 2,174,634

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL Filed Jan. 12, 1938 6 Sheets-Sheet l FIG. I.

Oct. 3, 1939. A. LESTI 2,174,634

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL I Filed Jan. 12, 1938 6 Sheets-Sheet 2 TNVENTOR I Oct. 3, 1939. A. LESTI 2,174,634

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL Filed Jan. 12, 1938 6 Sheets-Sheet 5 INVENTOR A. LESTI Oct. 3, 1939.

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL 6 Sheets-Sheet 4 Filed Jan. 12

[NvENToR MM Oct. 3, 1939. Q LEST] 2,174,634

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL Filed Jan. 12, 1938 6 Sheets-Sheet 5 IN VENT on Mali/L3 Oct. 3, 1939. A L -r 7 2,174,634

RADIO STATION CENTER TUNING PUSH-BUTTON CONTROL Filed Jan. 12, 1938 6 Sheets-Sheet 6 /8 I 1 I I INVENTOR Maxim Patented Oct. 3, 1939 UNiTED STATES .i' ATENT GFFiQE EIADIG STATKON CENTER TUNING PUSH- BUTTON CONTROL 10 Claims.

My invention is in a push-button tuning control to accurately tune radio receivers to transmitting stations by pushing or pressing corre sponding buttons. The present invention is also an improvement and extension of the disclosure in my previous application, Serial Number 137,509, filed April 17, 1937, for Radio station center tuning control.

An object of the present invention is to provide a radio push-button system wherein previous adjustments or settings are eliminated or greatly minimized and where the conventional operation, for push-button action, of adjusting to the resonance peak of a desired. station is err-- tirely eliminated. In this connection a feature of this invention is to permit the tuning mechanism to follow the station and tune itself in accordance with the exact position of the station transmitting whereby the station itself controls the exact stopping position.

Another object of my invention is to provide a push-button system that is self adjusting and self correcting when the radio receiver to which it is applied drifts or changes its tuning position. It is well known that such alterations occur due to changes of supply voltage and variations in temperature, humidity or aging of circuit components. In this connection an important object of my invention is to provide such self adjustments and such self corrections without modifying the alignment of the tuned circuits in the radio receiver thereby insuring perfect tuning by push-button control at all times. A detailed feature of the present invention is to provide motor actuation of the tuning system of the. radio receiver to which it is applied whereby the tuning system is moved in a novel manner by the shortest route or path to the desired station.

Another object of my invention is a provide a push-button control of the above type to operate as an adjunct of a radio station indicator of the general type described in my previous application above referred to.

In my previous invention I found that a series of shutters may be operated separately and independently and that the operated shutters may be held after the operative influence has passed to give a simultaneous visible indication of all the radio transmitting stations within the receptive range of the radio receiver. In my present invention improved forms of center tuning, to accurately obtain the center between the sides of the shutter indication, are utilized for pushbutton control of a novel type. I have found that motor scanning of the shutters may be utilized to give a shutter indication of the transmitting stations and the centering of such shutter indications permits the accurate positioning of the tuning element and to allow the positioning to follow the center of the shutter indication to give accuracy independent of the receiver circuit drift mentioned above. I have found that a series of pushbuttons may be used, each to control separate specified regions of the tuning range and. that accurate positioning of the tuning element by a motor drive may be effected by the above 1nentioned center of the shutter indication, which may be situated in any region under control of a particular push-button.

Another object of my invention is to provide a push-button control of the above type for radio receivers having several tuning ranges or hands and to allow such push-button tuning control of transmitting stations in any tuning band using the same series of buttons.

A further detailed feature of the present in vention is to permit accurate tuning of long distance and local stations under the control of a flip or momentary closure of a switch or pushbutton allowing the tuning mechanism to suddenly leave a given station and hunt accurately a neighboring station. Another feature is to en able the above flip tuning to render unnecessary any manual operation of tuning knobs either for local, distance or short wave stations.

Another featur of this invention is to provide a stable, simple and inexpensive push-button mechanism to perform the above objects.

With the foregoing and other objects and features in view which wiil be made manifest in the following detailed description and pointed out in the claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention wherein:

Fig. l is a front View of the indicator with escutcheon and attachment removed and showing also the control relays and motor drive system.

Fig. 2 is a View along line 2-2 of Fig. 7.

Fig. 3 is a sectional view on the line 33 of Fig. 1 showing also the escutcheon and attachments in section and the. manner of coupling the variable condenser of the radio receiver and commutator.

ig. 4 is a view along line 4-4 of Fig. 3.

Fig. 5 is a sectional view of the manual control knob.

Fig. 6 is an isometric view of the manual brake release linkages.

Fig. 7 is an enlarged View on the line '!'I of Fig. 1 illustrating only the centering feeler assembly.

Fig. 8 is a view in the line 88 of Fig. '7 showing part view of the movable slotted disc with feelers thereon.

Fig. 9 is a view of the line 'L-T of Fig. 1 similar to Fig. 7 but illustrating the double armature relay without the feeler assembly.

Fig. 10 is a view on theline l-|0 of Fig. 9 showing only the spring contact assembly and spring.

Fig. 11 is a part sectional view of a push-button and contact mechanism.

Fig. 12 is a diagrammatic View of the circuit connections also illustrating a method of applying the invention to a radio receiver.

Fig. 13 is an extension of Fig. 12.

Fig. 14 illustrates one form of the invention.

Fig. 15 is a view on the line 315-3 I of Fig. 14.

16 shows the shutter construction for the form of the invention as depicted in Fig. 14.

Fig. 17 illustrates another form of the invention.

Fig. 18 is a view on the line 3lB-3I8 of Fig. 17.

Fig. 19 is an isometric View of the slotted movable member required in the cylindrical form of the invention as illustrated in both Fig. 17 and Fig. 18.

Referring to the accompanying drawings wherein similar parts are represented by similar numbers throughout, it represents generally the movable relay which is rotatable with the variable condenser I1, in Fig. 3, of the radio receiver. The relay armature i8 is attracted magnetically to the core !9 when the relay coil 20 is energized as explained below. Finger 2| will then move several shutters 25 towards the protuberances 22, shown in Fig. 9, to spring these shutters slightly inward. Only one shutter such as 28 will travel through the slot 33 towards the back face I09 of disc 24. Rotation of the relay IS with disc 24, to which it is rigidly fixed, causes finger 2| to engage other shutters if the relay is energized. The shutters designated generally by 25 are held to the ring 26 integral with frame 21 by screws and washers 34. The feelers 29, 30 bear-against the shutters in the opposite direction to finger 2|. These feelers are positioned opposite the finger to permit their movement together with the shutters. superimposing of Fig. '7 and Fig. 9 illustrates this feature together with the protuberances 22 which makes possible the elimination of the feeler lift mechanism disclosed in my prior application. As a result of discontinuous operation of relay l6 and a rotation, the shutters will be scanned to give an appearance represented by 3! in Fig. 1. The indication 32 may represent a radio station transmittingduring the scanning period.

Disc 24 and relay it are held to shaft 35 by set screws not shown. I prefer a shaded pole type induction motor 35 to drive the gear train and entire assembly. Motor pinion 31 engages gear 33 which is integral with pinion 39. This drives gear 40 with pulley 4| belted to pulley 42 to turn gear 43 which, in turn, is coupled to rotate gear" 44 with pinion 45. Pinion 45 finally drives gear 46 which has a hub held to the shaft 35 by a set screw not shown. This arrangement is substantially similar to my prior disclosure except for the insertion of the motor drive and other important differences explained below.

When the movable relay assembly is rotated the motor is coupled to shaft 41 Fig. 3 by universal joint 48. Then rotation is given to wiper 48 which engages commutator segments generally represented by 49 on the commutator 50.

Elliptical gear 5! is fixed to shaft 35 and rotatable. Elliptical mate gear 52 is coupled with springs to 5|. Both gears 5| and 52 are coupled to elliptical gear 53 to eliminate back lash and provide substantially an evenly calibrated dial and avoid the crowding of stations on the low wave length side of the dial as shown in detail in my prior application. Gear 53 is coupled to variable condenser ll, fixed on the chassis 54 of the receiver, by coupling 55 with insulating washer 5B.

Relays 53, 55 with spring assemblies 60, 01 have armatures 32, 53 with forked ends 64, 65, engaging bushings 33, ii'l on brake rod 68 which engages the teeth of gear 43 when normal or restored by the spring 69 bearing against bushing held to brake rod. When relays 58, 59 are energized separately, as explained in detail below, their spring assemblies operate from the movement of rods H, 12, held to the armatures, against the traveling springs of 30, 61. The armatures are provided with residual screws 13, "I4 which, with back stop screws l5, l6, limit the movement and provide for adjustments to govern the speed of release and operate. The armatures hinge by pins "El, 18 on brackets '15, 85, which are made of magnetic material and form a part of the magnetic circuit of the relays having cores 8|, 82 and coils The relays are fixed by screws to the frame 85 which is integral with frame 21. I prefer to operate relay 53 to cause motor 36 to turn disc 24 and relay it, together with pointer 81, in the right or clockwise direction, while relay 59 will cause the motor to turn these members in the left or counterclockwise direction. When either spring assembly Bil, Si is operated to close the contacts, circuit connections are established which, while not shown in Fig. 1 to avoid confusion, are detailed in Fig. 13 and Fig. 12 and explained below, cause the operation of motor 36 and other circuit requirement also explainedbelow.

Brake rod 68 looks gear 43 when normal, as shown in Fig. 1, prevents the motor drive from turning the entire rotatable assembly and permits quick stopping ability. When armatures S2 and 63 are pulled towards the cores 8i and 82 forks 04 and B5 push bushings 55 and El and brake 38 against the spring 69 releasing the braking action on gear 43. The forks 54 and 65 are similar to fork I02 also shown in isometric form in Fig. 6. Relays 5S and 59 never operate at the same time and fork 64 disengages the brake independently of fork B5 and vice versa. When either relay is operated the motor drive is in motion and at the instant of release the brake plunges in the gear teeth stopping the same and the motor operating circuit is opened. In some cases the brake may be dispensed with.

In the drawings gears 43 and 44 are shown with coarse teeth for clearness. It is obvious that the spacing of the teeth on gear 43 will determine the points at which brake rod 53 may conveniently plunge to stop the tuning mechanism. The teeth on the gear 43 may be constructed as close together as is necessary to obtain the desired accuracy, while the turning ratio between shaft 35 and gear 43 may be also suitably chosen depending upon the kilocycle range for one full sweep of the tuning mechanism. Other suitable standard driving arrangements may be used.

Manual knob 83, in Fig. 3 and Fig. 5 is, provided for manual control if desired. The brake system must then be released and I prefer to establish such release by pushing the knob inwards before turning and holding the same inward during the act of turning. When the knob 88 is pushed inward clutch members 89 and 90 engage, linking the knob to gear 38 and the entire motor drive system. Sleeve 92 together with rod 9i having flange 93 are also moved inwards towards the frame. Split snap ring 95 prevents gear 38 from moving forward. Set screw 94 prevents knob 88 and sleeve 92 from being moved back excessively by stopping against flange 93 on rod 9i which is held from moving back by key 96. When rod 9| moves inwardly it pushes arm 97, Fig. 6, on shaft I00 against the restoring spring 90 riveted to the frame 21. A rotation of I00 will cause movement of rod 99 through linkage I03 to the right. Linkage I05 will transmit this motion from ID! to fork I02 through hinge I59. The fork moves to the right causing it to release the brake rod 58 in a manner similar to relay forks 64 and 65 mentioned above.

The feelers and their attachments and other details are omitted in Fig. 3 to avoid confusion. In Fig. 7 the feelers 29 and 30 with tapered edges are shown centered on the shutter indication I06. These tapered edges I35 and I 86 may have a small amount of hard substance fixed thereon to minimize wear. The shutters in both Fig. '7 and Fig. 9 are illustrated in section on the line I01, I01 of Fig. l. The feelers engage at points 225! and E08 of the shutters which are against the back face I09 of disc 24. When the disc 24 and its assembly rotates, the feelers move along with it but the shutters remain in the same radial position. The feelers will then articulate independently. When 20' moves to the left feeler 29 will rise and feeler 30 will lower. Feeler 23 will still make contact with contact tip I It! on the insulating assembly IIZ, which swivels on pivot screws and is given tension towards the feelers by spring H3. Feeler 30 will break contact with contact tip I II and spring downwards towards the shutters.

When the disc 24 moves to the right the opposite condition obtains wherein feeler 29 breaks contact with H0 and springs towards the shutters. The insulating rigid member I22 is provided with pivot screws to eliminate any twisting or lost motion. The feelers are provided with braces H4 and H5 held to arms HE and II! to prevent twisting during articulation and provide a sharp break with the contact points H8 and III. There are indentations or ribs H8, H9, I20, I2! along part of the length of the feeler arms to stiifen these members and permit movement only at the ends I22, 523, I24, I25. Feeler 29 moves with an axis from I22 to I 20 while feeler 39 moves with a similar axis from MS, I25. Contact points I I0, I! I both make with the feel ers when the assembly is centered on the indication such as I06 corresponding to the resonance of a radio station received. Adjustments of points H0 and III by nuts on the threaded portion of these contact points permit positioning the closing of both contact points on the feelers either to the right, left or exact center of the shutter indication. The feelers are used to stop the motor drive when the center of the shutter indication is reached, corresponding to resonance of a radio station received by the radio receiver, as explained in detail below.

Referring to Fig. 9 armature 58 having extension I26 is held normally away from the core I9 by spring I21 bearing against I 26. Finger 2| is welded on to the armature and moves with the same. The residual screw I28 and back stop I29, shown in Fig. 2 and Fig. '7, limit the armatures movements. The secondary armature I30, with residual screw ISI and back stop I32, moves independently towards the core !9 and is provided to operate the spring assembly of Fig. 10 at a different and generally later time than when the shutters. are operated. This secondary armature may be eliminated, in some cases, with the spring assembly in Fig. 10 being then operated by armature I8. There is an extension I33 on the secondary armature to operate contacts of the spring assembly having bushing I34.

Elevated portions %35 and I35 on the back face I09 of the disc M with corresponding front face indentation insure full quick restoration to the front face of the free movable springing end of the shutters during rotation of the disc. The shutters are self restoring by spring action to a position adjacent the front face I38 of disc 24.

I prefer to energize the relay Iii when the radio receiver is detuned, in which case the series of shutters held adjacent the front face 538 will constitute an indication of radio stations received as the tuning element of the radio receiver is varied. In this case the position of the shutters adjacent the front face !38 may be con sidered their operated position and after going through the slot while held on the back face I09, they may be considered as being in their normal position. However, in the alternative method of indicating the stations received, wherein blank spaces adjacent the front face I38 may correspond to stations received, the opposite nomenclature may be used, i.e., adjacent the front face I38 the shutters may be considered a being in their normal position while in the back face they may be considered as being in their operated position. Comparatively few shutters of substantial thickness are shown in the drawings for the sake of clearness. The shutters may be preferably a few thousandths of an inch in thickness and I have used 380 shutters to cover one megacycle sweep.

The shutter guide I39 prevents. the free movable ends MP3 of the shutters from touching feeler arms. There are lugs shown held firmly to the contact tips lie and Iii from which fiexible insulated leads may be connected to the insulated lugs N2 of terminal block II. Ends of coil 20 are connected to other similar lugs together with ends I 54 of spring assembly 3 The other ends I 03 of lugs it? connect to flexible insulated leads which may connect to ter-- minals held to the frame 2? or chassis 54, not shown, from which points I prefer to make circuit connections as detailed below.

While I have shown the shutters in a preferably semicircular forrn, this arrangement is not absolutely necessary. Where space is ample the shutters may extend substantially in a straight line. In this latter case the movable disc would have a straight edge and a slot similar to 33, while a relay similar to it would be fixed thereon and move in a straight line.

Fig. 11 illwtrates a part sectional View of a push-button mechanism of a general type. There are many push-buttons such as M8 and Ml. Push-button i6! is shown depressed with a tapered section I56 held by movable member 545 which is pushed towards the left by spring I50. Contacts I52 and W3 are shown made. If pushbutton M5 is depressed against the tension of spring I48, tapered section I55 will move into hole I51 pushing I45 towards the right allowing M1 to rise by the action of compressed spring M9 to push this button through the hole provided on I45 and thus break the contact at I52 and I53. Push-button I48 will stay in a depressed position when movable member I45 latches the top of tapered section I55, permanently making contact Hit, 254'. This type of mechanism may be conveniently used with the present invention to obtain push-button control whereby a button such as either I 38 or I41 may correspond to a radio station within the receptive. range of the radio receiver to which this invention is applied, and when the push button is depressed the tuning mechanism will be turned by the shortest route to that station and stop accurately on the resonance point of that station.

In Fig. 12 lead I58 goes to the secondary of the intermediate frequency transformer of which the primary is connected to the amplifying tube preceding tube 59 or 60. The part of the receiving circuit which precedes these tubes is conventional and preferably of the superheterodyne type and the condenser I1, shown in Fig. 3,

constitutes the variable tuning element of the receiver to which this novel invention is applied.

I prefer to apply intermediate frequency potentials from lead I58 to control the grids of tubes I59, I89. Tube I68 provides an amplified output to the diode I63 through transformer IiSI, which rectifies the intermediate frequency currents and establishes a negative potential on lead I82 the magnitude of which is proportional to the intensity of the carrier of the received signal. The lead IE2 is fed to the conventional automatic volume control circuit of the receiver. For quick scanning it is better to maintain resistance 584 lower than the conventional and the by-pass condensers in the automatic volume control lead should preferably be lower capacity than the conventional, to permit quick charging and discharging of this circuit. A full wave rectifier system may be used instead of the half wave system shown either for the circuit connected to tube IE3 or IE5.

While I have shown separate amplifying tubes I59, I69, this arrangement is not absolutely necessary as other arrangements, well known to the art, may be used. The secondary of transformer iEI may be inductively coupled to the primary of transformer I56, thus eliminating tube I69 when great sensitivity is not required.

The amplified output of tube I59 is fed to diode I85 through transformer I85 to provide a negative potential, with respect to ground, at point IG'I, the magnitude of which is also proportional to the intensity of the carrier of the received signal. A positive potential is superimposed at I58 to add to the negative potential on I81 from the source of potential I1! from lead I12 to voltage dividing resistors I19, I18. Switch I59 is coupled to the wave band switch of the receiver allowing different resistances to be cut in, similar to I13, with a value depending upon the general noise level and sensitivity of the receiver on that band. Demodulated voltages are fed to audio amplifying tube I14 and thence to the rest of the audio frequency amplifier, not shown, from lead I15. The potential at I91 is also fed to the grid of the tube I'I'I through limiting resistor I16 to limit the load on the diode circuit whenever the potential swings in the positive direction. Tube I11 is directly coupled by resistance I82 to tube I19. To maintain the proper phase the coupling lead is fed to the cathode I89 and the grid is held at a fixed potential by lead I8I. Coupling resistance I82 is shown with by-pass condenser to filter out the audio currents in this circuit. A source of potential I83 supplies both heater and plate current for tube I19 as shown. The grid of tube I11 is normally held at a potential to cause the plate current to have a high current flow, maintaining I84 at a comparatively low positive potential and causing lead I8I to be at a low negative potential with respect to I89, thus allowing tube I19 to pass a high plate current, energizing coil 29 of relay I6 and causing both armatures of this relay to be pulled up towards the core when no stations are being received.

If scanning takes place with no stations being received the shutters will all be pulled towards the back face of the disc 24 by the action of armature I8 and finger 2 I. When a radio station is received a high negative potential will be placed at point I61, which will be maintained for a considerable range on both sides of the exact point of resonance of the station. This negative potential causes the plate current of tube I11 to lower in value or cut off. The positive poten tial at I84 will then rise, making 58! relatively negative by comparison, thus lowering or cutting off the plate current of tube I19. This will release both armatures of relay IS with a consequent springing back through the slot 33, of the shutters, thereby establishing an indication such as 32 in Fig. 1. During the time of scanning, either to the right or left, any radio station received will produce a similar effect at the proper corresponding part of the dial. The automatic volume control potential at I82 should be sufliciently high to properly minimize the variations in the width of the indications of all the stations received. Tube I11 may be eliminated, in some cases, with the grid of tube I19 connected directly to IE1.

Referring to both Fig. 12 and Fig. 13 tube 591 is coupled with resistance I99 to both tubes I88 and I89 with the grid of tube I81 maintained normally for plate current cut-off of both I88, I89. The plate of tube I81 is connected to the grid of tube I88 and the cathode of tube 589, while the cathode of I88 is maintained at a potential with respect to its grid for normal plate current cut-01f and the grid of i89 is maintained L at a potential, with respect to its cathode, for normal plate current cut off of this tube. lhese tubes are furnished with sources of heater plate current I9I, I92. The plate circuit of tube I88 includes coil 84 while that of I89 includes coil 83 allowing these tubes to control relays 58 and 59. Whenever the potential on the grid of tube I81 changes in the positive direction there will be a lowering of potential at I93. This will cause the grid of tube I89 to become more positive with respect to the cathode, allow plate current to flow, energize coil 83, operate relay 53 and cause the motor drive to scan in the right direction. When this takes place tube I88 is maintained at plate current cut-off.

When the potential on the grid of tube I31 changes in the negative direction there will be a raising of the potential at I93. This will cause the grid of tube R88 to become relatively more positive with respect to the cathode, allow plate current to flow in tube I98, energize coil 84, op:- erate relay 59 and cause the motor drive to scan in the left direction.

I prefer a source of alternating current 5 2 for induction motor 36 with a lower voltage for the shaded poles as shown. It is to be understood, however, that other suitable direct or alternating current motors may be used in a known and standard manner. Reversal of the motor takes place by reversing the leads to the shaded pole coils as shown.

A locking lead I is provided to receive a positive locking potential if relay 58 is operated and a negative locking potential if relay 59 is operated. This lead connects indirectly to the grid of tube I87 and provides a high potential for this tube of a polarity similar to that which may have been placed on 31. It is to be understood that the use of a positive potential to control the right direction of travel may he obviously changed by suitably altering the proper leads.

While I have shown five push-button contacts 261 to simplify the diagram in Fig. 12, it is to be understood that any larger amount may be used and I have actually used 26 push-buttons. Resistances are used to form a voltage dividing system so that any push-button, when depressed, will connect a diiterent potential on taps 295. The commutator segments it are connected to the voltage taps 225 through crossconnecting block 24 which. permits any segment to be connected to any tap. I prefer to have twice as many segments d9 as push-buttons. In some case it may be advantageous to connect three segments to one tap and the next segment may connect to an individual tap. Other suitable relations may be used. The potential of any push-button contact such as I52 is similar to the potential. at 206, when a contact such as i53 is closed as shown. With respect to the operating conditions on tube 481, I88 and 1853 this potential may be considered as being zero potential. All contacts on 25.52 will have either a positive or negative potential with respect to a depressed push-button contact according to whether or not the contacts are to the left or right position with respect to that depressed contact. In Fig. 12 commutator Ed is shown in a rear view similar to Fig. 4, so that when. the wiper 48 rotates to the left the disc 24 and its assembly actually rotate to the right. If wiper 48 should be contacting segment 20?, with I52 and I53 closed, there will be a negative potential on 22! which will be applied to the grid of tube I81 by going from the wiper 43 to resistance I91 to 2839, 2|, 215 through contacts on switch 260, 2 i2 and to the grid. This will cause the motor drive to move the wiper towards segment 22 i. If the wiper was contacting on segment 2118 a positive potential from 55! would be similarly applied to the grid of tube it! to cause the reverse motion to take place until the wiper reached segment 22!. On. segment 22! motion will be maintained by the locking potential coming from lead I25; provided, however, that the relay i5 is operated and relay contacts 2H! and 22! are made and 2H} and 2% opened, corresponding to a condition when no radio stations are received. If a radio station is received any place within the range occupied by segment Hi, the armatures on relay it? will be restored, contacts 212 and 22! will break while 2|!) and 209 will make and control will be transferred to the feeler circuit leading to point 222. When relay I6 is energized the locking circuit is maintained, when the wiper is on segment 22! by the potential drop on resistance @535. When relay it is restored resistance I96 is no longer effective and the locking lead potential is shunted by the wiper and contacting segment, while simultaneously control is transferred to the feeler circuit. I prefer to insulate the frame 21 from the radio chassis 54.

If feeler 29 is raised above feeler 353 there is a detuned condition to the left of the resonance point of the station received. Contact point H0 will be closed with 29, but contact point HI will be opened from 30, causing current to flow through resistance 223, 225 and 226 to point 205. A positive potential, with respect to 266, will develop on 226 which is applied to the grid of tube I81 causing a movement to the right to correct the detuned condition to the left. If feeler 33 is raised above 29 the opposite condition obtains by the action of resistances 224, 225 and 22%, causing a negative potential on 222 which is applied similarly to the grid of tube I87 to cause a movement to the left to correct the detuned condition to the right. When the exact center of resonance is reached both feelers make contact and the potential of 222 is zero with respect to 206, allowing the relays 5-5 and $3 to restore and apply the brake to quickly and accurately stop the motor drive mechanism. Commutator segment 22! corresponds with push-button contacts I52 and !53, however, the same results are obtained on any segment which may be connected to contacts of a depressed pushbutton.

The elliptical gears 55!, 52 and 53, illustrated in Fig. l, are not required if variable condenser ii is of the straight line frequency condenser type. Standard circular gears with a one to one speed ratio may be substituted, or other method utilized to couple l'l to shaft 35.

In Fig. 14 character 250 represents the movable member with slot 25!. This member moves in a straight line and corresponds to member 24 in the other system described above. The shutters 254 are shown drawn to a larger scale in Fig. 16 and extend substantially in a straight line. The core of the relay 2G8 holds the pointer 253. The relay 268 is fastened to 250 and moves either to the right or left as 259 is moved by the engagement if gear 255 to teeth 269. Gear 255 is equipped with springs such as 256 to prevent back-lash in the conventional manner. Shaft 261 which drives gear 255, may be coupled with suitable back-lash eliminating gears, to a shaft similar to 35 of Fig. 3. The gear ratio would be such that a half revolution of 35 would cause shaft 261 to rotate gear 255 and move 253 the entire distance occupied by the shutters. Other suitable standard means may be used to move 25%].

In the cylindrical form frame 213 corresponds to 27 of Fig. 3. The shutters 214 may be similar to those illustrated in Fig. 16, and curved as in Fig. 1'7 and Fig. 18. The pointer 215 is held to the core of the relay 216, while the movable slotted member 21 I, with relay 2'56 fixed thereon, is rotated by shaft 212, which may be suitably coupled to a shaft similar to 35 of Fig. 3 by known and standard means. In some cases shaft 35 may stand in the vertical position, thus per mitting a simplified coupling arrangement to shaft 212, if this is also in the vertical position.

When a push-button is depressed the initial contact voltage is linked to tube I81 through resistance I91. Switch 228 has a left control position I99 and right control position I98 to impress a corresponding positive or negative potential on the grid of tube I87 for independent left and right control. I prefer to have this switch self restoring by spring action in either direction. The locking lead I955 is opened when the switch is operated in either direction.

Switch 2% allows the elimination of the automatic motor drive control, when operated, by opening the grid of tube I81 from the control circuit and holding itspotential fixed to that at 206 through resistance 228. Manual control with the knob 88 is then possible. Contacts 22% and 23% provide interstation noise suppression for manual control, by shunting the audio lead M5 to ground, except when stations are received. Lead 249 must then be independently grounded by switch 24!.

Lead 2H is connected to spring assemblies 68 and 6! for the complete suppression of the audio circuit when the motor drive is actuated. The operation of switch 200 eliminates the noise suppression feature.

I prefer to construct all shutters, illustrated in Fig. 1, Fig. 16 and Fig. 18, from one piece of thin sheet spring metal with a free end and a fixed end for all shutters, as detailed in Fig. 16, but it is to be understood that each shutter may be constructed as a separate distinct piece and suitably mounted adjacent to each other.

When switch 221 is closed and push-button control is shunted out so that a momentary operation of the switch 228, either to the right or left, will cause the tuning mechanism to suddenly leave a given station and move automatically to a neighboring station, thus obviating the need of the tuning knob 88. When no pushbuttons are depressed the wiper 48 may move continuously without stopping. Automatic reversal takes place at the end positions, due to the increasing potential on the segments towards these positions, with a polarity opposite to that of the locking lead 155 which is neutralized and the opposite potential established on the grid of tube !81, and thus causing a reversal in the direction of travel.

The following is a short rsum of the operation of the system:

Referring to both Figs. 12 and 13, the potentials established at I62 and IE1 are developed in the known and standard manner. The negative potential at 161, the magnitude of which is proportional to the intensity of the carrier of the received signal, is fed to the grid of tube ill. The return circuit is grounded as shown. A circuit may be traced from source of potential I'll to positive lead I12, through resistance i132, it'd, to the plate of tube I11, cathode of this tube to ground, and from ground through a resistance b to M9 which terminates back to the negative side of ill. The potential across resistance i8 2 is directly coupled to tube I19 at its, liiI, with the phase connections being such that a large negative potential at H51 will cut-oh the plate current of tube I19 and restore the armature of relay it. An independent source of plate potential 583 is connected from positive lead to relay coil 28, plate of tube 519, to cathode its, and back to the negative side of I 33, causing current to flow. Armature 2i operates the shutters in accordance with the stations tuned in as scanning takes place.

When the receiver is turned on, all sources of potential will become established and automatic scanning will take place, unless a push-button may be depressed corresponding to a position to which the receiver may be tuned; or if the flip control switch 221 is operated. Assuming the wiper 48 is. engaging a segment such as 2418 at a positive potential with respect to 208. A

circuit may be traced from wiper 48 to 242, through resistance N31 to 222, contact 299 to 2st, 2E5, through contacts on switch 20%, back to 2I2 and to the grid of tube I81. The wiper potential may thus control tube I81. The cathode potential of tube I81 is kept positive with respect to point 236 which furnishes normal grid bias for this tube, at a value sufficient to maintain tubes I88, I39 at normal plate current cut-ofi. In the instant assumed a positive potential on the wiper is transferred to tube I31, swinging its grid in the positive direction above normal bias.

Tube N31 is directly coupled to both tubes I88, Hi9. A circuit may be traced from positive of WI at I12 to M8, through resistance I9I!, I93, lead 253, to the plate of tube N31, to its cathode, through resistance to 2%, ground and resistance 4953 to the negative side of 11!. The plate of tube I81 is directly connected to the grid of tube I 88 and the cathode of tube I89. The cathode of ISE'; is held at the same potential as I12 for normal plate current cut-off of this tube, while the grid of N39 is maintained at a comparatively negative potential, also for normal plate current cutoil.

In the instance mentioned, when the grid of I81 swings in the positive direction, the potential at 93 will be lowered, due to the increased current flowing through resistance 196. This causes the cathode of I89 to swing negatively, thereby its grid will swing relatively in the positive direction, causing current to flow in the plate circuit of this tube. A circuit may be traced from the positive side of potential source I92 through coil 83, the plate of I 89, cathode, and back to the negative side of I82. The current flowing in this circuit will cause relay 5%! to operate closing all the contacts 6%. This causes motor 36 to turn the tuning mechanism. in the right direction. Independent alternating currents from source I94 may be traced through operated contacts of 69 in the conventional manner to motor 36. Wiper 48 will leave segment 288 and move towards segments 221, 201.

When contacts 69 close, a circuit may be traced from positive lead H2, 2H3, through a limiting resistor, to closed contacts of 6D, to locking lead I95, through the make before break contacts on switches its, I98, to lead 2 I4, and to contact 22!. .t the positions. where no stations are received by the receiver, relay i6 is energized and closes contacts 22!, 2M]. The locking lead is then traced to 2 Hi from which the circuit has already been traced to the grid of tube I 81. Where stations are received, relay IE3 is not energized and the locking lead at 2M may be traced through resistance I96, to wiper 48 and an engaged segment, to resistance 2&2, to the negative side of I'll, if the locking lead has a positive potential. The wiper will then have a positive locking potential due to the potential drop across that portion of 2512 between a push-button depressed contact and a wiper engaged segment. This voltage is transferred to the grid of tube I81 through lead 242 already traced.

A small initial potential linked to control I81 will cause an operation of relay 58 or 59, causing a IOCkil'lg voltage to be placed back on the grid of I81 to reinforce the original potential. As the wiper travels, the segments which are contacted have an increasingly negative potential, in the instance mentioned, and at the last segment the locking potential on the wiper is overcome and additional potential of opposite polarity is provided. This new potential is transferred to the grid of tube I87, causing a raising of the positive potential at I93, due to the decreased current through resistance I9i). This causes the grid of tube I88 to swing in the positive direction with respect to its cathode. A current will flow from the source I 9I which may be traced from positive at I9I, through coil 84, to the plate of tube I83, to the cathode, and to the negative side of ISI.

Relay 59 will then operate to move the motor 36 in the left direction. The connections of 6I are similar to those of 60, except for the standard reversal of the shading pole leads as shown. A circuit may be traced from the negative lead 259 through limiting resistor, to closed contacts of 6!, to locking lead I95. From this point the operation is similar to that caused by a positive potential, except for the reversal of polarity and direction.

Continuous scanning with automatic reversal takes place as explained above. The stations on the air will then give the shutter indication. If a push-button is depressed such as M3, the potential at 206 is transferred by I53, I52 to segment 22 I. When the wiper 48 arrives at this seg--- ment the locking potential at 242 is shunted out insofar as its effect on tube I8! is concerned. The locking potential will be still effective on tube I81 to maintain motion, however, so long as relay I6 is energized corresponding to positions in the tuning range where no stations are received. The locking potential at H4 is then transferred from ZZI to 2m, 2E5 and thence to the grid of tube I 81, as previously traced. The locking potential drop across 526 is then utilized.

Motion will be maintained on segment 221, even though push-button IE3 is depressed, if no stations are received. If a station is received any position of segment 22!, relay I6 restores, opening contacts ZZI 2| fl and removing the locking potential from tube I8! and transferring control to the feeler circuit from 2!!! to 209 to 222. As detailed previously a positive potential is placed on 222 when there is a detuned condition to the left and a negative potential is applied when there is a detuned condition to the right. This potential is placed on the grid of tube I31 to cause the required correcting movements. When the resonance point is reached the brake 68 is released to stop the tuning mech anism. The potential at 222 is then similar to that at 236, since lead 2% may be traced to 24 to both 29, 33, to H0, MI, 225, 225 and 222. This holds It? at normal bias with I88, 589 at cut-01f and relays 58, 59 normal.

If pushbutton I 54 is depressed, I53 will 1' lease, and contact 552 will have a negative potential with respect to I5! which becomes. reference point at a potential similar to 206. This negative potential at I52 is then transferred to the grid of tube I87, as explained previously, causing a homing movement by the shortest route of the wiper towards the segment on the commutator connected to I5I.

If switch 22'! is closed to 203 the entire pushbutton and commutator unit is shunted out and rendered as if all push-buttons were depressed. If the flip control switch I98 is then operated, a positive potential is linked from ZIB to 2H! causing movement in the right direction. The locking lead I may connect directly to 2M eliminating connections on switches 198, I99, if the limiting resistors are held at a close value to prevent neutralizing of potentials if the opposite polarity is operative when the flip switch is operated. Switch I99 causes the opposite movement when operated. Both switches are self restoring permitting the locking lead to maintain motion in whatever direction the motion may have been started by the momentary flip. Such motion continues until a station is reached at which position the feeler circuit will accurately control the stopping.

During the time of travel, while the mechanism may move from one station to another, actual scanning is taking place to correct the shutter indications if necessary. Should there be variations in the constants of the radio receiver, to cause changes in the positions of the stations, the new positions will thereafter control the stopping of the tuning system. The same conditions apply in any wave band to which the receiver may be receptive.

Various changes may be made by those skilled in the art in details of construction of my invention without departing from the spirit thereof as set forth in the drawings, specifications and claims.

I claim:

1. A signal tuning control comprising in com- I bination, a receiver having a tuner, a series of shutters adapted to be moved, a movable member coupled to the tuner and having a relay adapted to be operated, an armature on the relay having a finger adapted to move the shutters, means for utilizing the receiver to operate the relay in accordance with the signals received, a motor drive adapted to move to the left and right directions and coupled to the tuner to operate the same, a locking lead with means cooperating therewith to maintain motion of the motor drive when the relay armature is positioned corresponding to a detuned condition of the receiver, and contacts on the relay to disengage the locking lead when the armature is operated in accordance with a tuned in signal with means engaging the moved shutters to stop the motor drive on the tuned in signal.

2. A radio tuning control comprising in combination, a radio receiver having variable tuning a means, a motor to drive said means, a series of shutters, a member coupled to said means and movable relative to the said shutters, and adapted to operatethem in response to the tuning-in of a signal, and means controlled by operated shutters to stop said motor.

3. A radio tuning control as claimed in the preceding claim with the last mentioned means including a centering switch adapted to stop the motor on substantially the center of a group of operated shutters, corresponding to the position of resonance of the said variable tuning means with a tuned-in signal.

4. A radio tuning control comprising in combination, a radio receiver having variable tuning means, a series of shutters, a member coupled to the said tuning means and movable relative to the shutters and having a relay adapted to operate them in response to the tuning-in of a signal, a manually operated switch with means adapting the same to start the motor in either the right or left directions, locking means to maintain the motor driving when the said switch is restored, and means controlled by operated shutters to stop said motor.

5. A signal tuning control and indicator comprising in combination, a signal receiver having variable tuning means, a motor to drive said means, a series of shutters, a member coupled to said means and movable relative to the shutters,

iii

and adapted to operate them in response to the tuning-in of a signal to give a visible indication, and means controlled by operated shutters to stop said motor.

6. A radio tuning control comprising in combination, a radio receiver having variable tuning means, a motor drive to drive said means, a right relay to control the motor in the right direction, a left relay to control the motor in the left direction, a brake with a force acting normally on the motor drive to stop the same, an armature on each relay linked to the brake and adapted to operate the same independently, and means responsive to a tuned-in signal controlling the release of the brake to stop the motor drive.

'7. A radio tuning control comprising in combination, a radio receiver having a tuner, a series of shutters each having a normal and an operated position, means for operating the shutters when the tuner is receiving signals, a centering switch to center on the operated shutters and having means cooperating therewith to give a potential when off center to the right of opposite relative polarity to the potential when off center to the left, a motor drive coupled to the tuner adapted to start and stop and have a direction of travel dependent upon the potential given by the said centering switch whereby the motor drive moves by the shortest route to the center of the operated shutters corresponding to resonance of a radio station received.

8. A radio tuning control comprising in combination, two feeler members adapted to be moved in dependently, a movable member having contact points adapted to be moved in unison and engage the feeler member, means for disengaging one feeler member from its contact point by the movement of the other feeler member, bridging resistors connected to the contact points and having a common ieeler lead and potential resistors also connected to the contact points whereby said feeler lead will have a relative polarity with respect to the feeler members similar to the polarity of the potential resistor connected to a disengaged contact point.

9. A radio station tuning control comprising in combination, a radio receiver having a tuner, a series of shutters adapted to be moved, a movable member coupled to the tuner and having a relay adapted to be operated, an armature on the relay having a finger adapted to move the shutters when the relay is operated, means for holding the moved shutters, means for utilising the receiver to operate the relay in accordance with the radio stations received, a motor drive adapted to move to the left and right directions and coupled to the tuner to operate the same throughout its entire range, a centering switch engaging the held shutters and having means cooperating therewith to stop the motor drive, a commutator with a series of segments having means cooperating therewith to control the direction of travel of the motor drive, a wiper adapted to engage the segments and coupled to the tuner, a series of push buttons each adapted to connect a segment, a locking lead with means to maintain motion of the motor drive when the wiper engages a push button connected segment, contacts on the relay adapted to disengage control of the locking lead and to transfer control of the motor drive to the centering switch when the relay is operated.

10. An electrical control comprising in combination, a signal receiver having a tuner, a motor drive coupled to the tuner, a right relay adapted to control the motor drive to the right when energized, a left relay adapted to control the motor drive to the left when energized, a right amplifying tube to control the right relay, a left amplifying tube to control the left relay, a series of resistors arranged for tapped potential division, a series of contacts each adapted to connect a tap on the said potential dividing resistors, a commutator having a series of segments connected to the said potential taps, a wiper to engage the segments coupled to the tuner and giving a potential corresponding to an engaging segment and of a polarity dependent upon the relative direction of the push button connected segment, a control lead common to both right and left amplifying tubes having means adapting the same to provide control potential for the tubes, and means for applying a potential by the wiper to the control lead whereby the right tube is excited to energize the right relay by a potential of polarity opposite to that required for the left relay.

ARNOLD LESTI. 

